Toroidal reed switch



E. F SIDOR ETAL TOROI Nov. 25, 1969 2 Sheet Filed July 1, 1968 NOV. 25, 1969 E s g'c ETAL TOROIDAL REED SWITCH- 2 Sheets'Sheet 2 Filed July 1, 1968 FIG. 2

FIGB

United States Patent 3,480,893 TOROIDAL REED SWITCH Edward F. Sidor, Lombard, and William A. Reimer,

Wheaton, Ill., assignors to Automatic Electric Laboratories, Inc., Northlake, Ill., a corporation of Delaware Filed July 1, 1968, Ser. No. 741,525 Int. Cl. H01h 9/02, 13/04 US. Cl. 335-202 4 Claims ABSTRACT OF THE DISCLOSURE A toroidal housing contains pairs of arcuate reeds with fixed ends mounted on a plug extending radially from the housing. Either a single housing or a plurality of housings arranged coaxially functions as a bobbin for an operating winding.

Background of the invention This invention pertains to electromagnetic switches and particularly to reed type relays with toroidal housings.

Reed type relays are used to provide faster operation that that obtainable by electromagnetic armature type relays. Commonly, a pair of straight reeds are encapsulated in a straight length of glass tubing. Even though the relay is made as short as practical, the terminals extending from the ends of the tubing are widely separated in comparison with the separation of terminals in a usual connector. For a straight reed relay to be adapted to a usual plugin or connector arrangement, a relatively 10nd strap is needed between at least one of its reed terminals and a connector terminal.

The operate Winding of a usual straight reed relay is a solenoid winding placed on the glass tubing which contains the contacts. To increase the efficiency of the relay and to prevent interaction with adjacent relays, its magnetic field may need to be confined by bridging the external ends of the reeds by a magnetic circuit outside its winding.

US. Patent 3,278,871 issued to G. V. Deverall on Oct. 11, 1966 shows a switching device with curved contacts. Through this arrangement, the fixed ends of the reeds are close enough together to be connected directly to terminals of a plug. In the Deverall switch, plug terminals extend from the base of the cylindrical housing, and curved operating coils wound about the curved contacts are located inside the housing. Although the switch is small, the reeds are longer than those in many types of relays with straight reeds. The combination of longer reeds and curved operating coils provides operation of contacts with low operating current.

Summary of the invention The present relay has curved contacts mounted Within a toriodal housing. The housing also functions as a bobbin for a toroidal winding which covers all the housing except for a small portion at a connecting plug. The plug extends radially through the outer wall and supports the curved contacts of reeds within the toriodal housing free of its sides. After the contacts are sealed in the housing, the plug does not interfere with application of either a single operate winding or a plurality of windings suitable for use in a matrix. Neither atmosphere nor the subsequently applied windings can contaminate the contacts within the sealed housing.

Different combinations of normally open and normally closed contacts can be readily provided. A plurality of pairs of curved reeds arranged like rings and mounted to a single plug can be enclosed within a single housing.

3,480,893 Patented Nov. 25, 1969 ICC The rings may be mounted parallel in different planes, or they may be mounted concentrically in a plane. A plurality of housings can be arranged coaxially in a column as a unit. Alignment means are provided to facilitate stacking the housings.

Brief description of the invention FIG. 1 is an enlarged, exploded, perspective view of a toroidal housing assembly and a contact assembly of the relay of this invention;

FIG. 2 is a perspective view of a relay comprising a plurality of housing assemblies and contact assemblies of FIG. 1 arranged in a column with a toroidal winding on the column; and

FIG. 3 is a cross section of FIG. 2 on a line 33.

Description of the preferred embodiment The contact assembly of FIG. 1 comprises two pairs of arcuate reeds 11-12 and 13-14 arranged as parallel rings and attached to a connector plug 15. The free end of each reed has a contact portion 16, and its fixed end 17 has a terminal portion extending through the plug 15 to provide a connecting terminal 18. The plug 15 may be fabricated from a stable insulating plastic, or a glass header may be used instead. The reeds 11-14 are fabricated from magnetic and electrically conductive material.

The pairs of reeds 11-12 and 13-14 may be arranged so that their contacting surfaces overlap as shown in FIG. 1, or both reeds of a pair may be mounted with their contacts operating over nearly the same are so that when the relay is operated the contacts meet end-on. The use of overlapping contacts can provide wiping action during each operation. Usually, the end-on contacts are plated with precious metal to provide low electrical resistance when the contacts are closed.

The pairs of reeds 11-14 may be fabricated from materials of different shapes. For example, in FIG. 1, rectangular reeds are shown with their greater cross-sectional dimensions parallel with the axis of their arcs. Alternately the reeds can be mounted with their greater dimension in the direction of the radii of their arcs, and then the overlapping type contacts are used, the contact ends may be twisted in an acute angle with respect to the rest of the reed. Alternately, the reeds may be fabricated from round wire or rod and have only their ends flattened.

The spacings between the contacts of the pairs of reeds 11-12 and 13-14 are adjusted before they are enclosed in their housing assembly. The contacts are adjusted so that they close with predetermined magnetization. Either permanent magnets may be brought within a specified distance or the contacts to provide the magnetization, or a conductor may be passed through the ring formation of the contacts and a predetermined current passed through the conductor to test for operation of the contacts. For this latter method, a clip-0n coil similar to those used to measure alternating current in power lines without breaking the lines, may be designed especially for convenient use in adjusting the contacts.

After the reeds of the contact assembly are adjusted, the assembly is positioned in its toroidal housing which comprises the mating parts 19 and 20 molded from insulating plastic. Each of the toroidal housing parts 19 and 20 is open at its base to expose a circular cavity 21 between an inner portion 22 and an outer portion 23 of its wall. The terminals of the reeds 11-14 within the terminal plug 15 extend through an opening 24 in the outer portion of the wall, and a rectangular support 26 extends outwardly from the edges of the opening 24 to receive the plug 15. The contact assembly is placed in one part of the housing such that a shoulder 27 of the plug 15 fits into a groove 25 in the end of the support 26 where it joins the outer wall 23. Each of the parts 19-20 has the edges 28 of the wall 22-23 rabbeted to facilitate joining and sealing the edges. A suitable sealing technique may be used to seal the seams between the two housing parts 19 and 20 so that the housing can contain inert gas. The adjusting, testing, and assembling of the contact assembly into its housing may be done in an inert atmosphere.

After contact assemblies are enclosed in their housing assemblies, a toroidal winding is wound on each housing assembly or on a plurality of housing assemblies aligned in a column. In FIG. 2, a housing assembly 30 with two sets of contacts corresponding to that shown in FIG. 1 is aligned coaxially above a housing assembly 31 which contains four sets of contacts. Various combinations of contacts may be used. For example, the contacts in the housing assembly 30 may be normally open contacts, whereas the contacts in the housing assembly 31 may be normally closed contacts. The housings of the assemblies 30 and 31 function as a bobbin for the winding 33. The winding covers the entire housings except for the small portions where the plugs project outwardly from the toroid.

For those switches requiring more than one housing assembly, various alignment means may be used to facilitate the positioning of the housing assemblies into columns. For example, as shown in the accompanying figures, a groove 29 is molded into those faces of the housing which are to be contiguous with an adjacent housing. A resilient O-ring 32 as shown in FIG. 3 fits tightly into adjacent grooves of housing assemblies arranged in a column.

Small relays constructed with radial terminals according to this invention can be inserted in closely spaced relay sockets to achieve high packaging density on relay circuit boards. Typically, the diameter of a toroidal bobbin, before the winding is applied, is about 1 inch, and its thickness is about /2 inch. The windings of a matrix of toroidal relays may be connected through radial plug-in terminals or the windings can be continuous or directly connected. The open centers of the toroidal switches facilitates placement of common windings on columns of adjacently mounted relays.

What is claimed is:

1. A toroidal reed switch comprising:

a reed switch contact assembly having a pair of arcuate spring reeds of electrically conductive and magnetically permeable material and a terminal connector,

each of said reeds having a fixed end mounted to said terminal connector, said pair of reeds forming a ring with an insulating gap between said fixed ends and mating switch contacts at their free ends,

a toroidal housing assembly of insulating, non-magnetic material, said housing assembly having a coaxial cavity and an opening through the outer portion of the wall of said cavity, said housing assembly being fabricated from at least two parts, said cavity and said opening being freely accessible before assembly of said parts to receive said reeds and said terminal connector, respectively, said terminal connector fitting securely in said opening to support said reeds in said cavity free of the sides of said housing assembly when assembled, and

a toroidal winding on said housing assembly.

2. A reed switch according to claim 1 having a plurality of said pairs of reeds mounted on said terminal connector, said pairs being mounted in different parallel planes.

3. A reed switch according to claim 1, having a plurality of said toroidal housing assemblies containing respective pairs of said reeds, means for aligning said housing assemblies coaxially in a column, and a toroidal winding wound on said column of housing assemblies.

4. A reed switch according to claim 3 in which said means for aligning said housing assemblies includes a resilient O-ring, each of said housing assemblies having a groove in its surface Where it is tangent to the surface of the adjacent one of said housing assemblies, said resilient O-ring being disposed tightly in the grooves between each of said housing assemblies and its adjacent housing assembly.

References Cited UNITED STATES PATENTS 2,906,978 9/1959 Mikesell 336229 3,070,766 12/1962 Purdy 336-198 3,171,918 3/1965 Killion 335-202 3,278,871 10/1966 Deverall 335-l54 BERNARD A. GILHEANY, Primary Examiner H. BROOME, Assistant Examiner US. Cl. X.R. 

